Gas vent

ABSTRACT

A method and apparatus for venting hydrogen sulphide gas from a vessel or tank car containing hot molten sulphur therein, wherein a layer of sulphur crust has formed on the upper surface thereof and conventional venting arrangements are non-functional due to blocking by solidified sulphur. A hot fluid is passed through a conduit so as to melt a hole in the sulphur crust around the outer periphery of the conduit and thus permit trapped hydrogen sulphide gas from the area below the crust to pass upward therethrough. The hydrogen sulphide gas is then vented from the area above the crust to the outside of the vessel.

Deeks United-StatesPatent 11 1 [s41 GAS VENT Ronald G. Deeks, Oakville,Ontario,

Thompson ..l37/340X 1 May 1, 1973 1,602,887 10/1926 Florez.......137/34ox Primary Examiner-Alan Cohan Attorney-Charles M. Kaplanand Joel E. Siegel 571 ABSTRACT A method and apparatus for ventinghydrogen sulphide gas'from 'a vessel or tank car containing hot moltensulphur therein, wherein a layer of sulphur crust has formed on theupper surface thereof and conventional venting arrangements arenon-functional due to blocking by solidified sulphur. A hot fluid ispassed through a conduit so as to melt a hole in the 'sulphur crustaround the outer periphery of the conduit and thus permit trappedhydrogen sulphide gas from the area below the 'ClUSt to pass upwardtherethrough. The hydrogen sulphide gas is then vented from the areaabove the crust to the outside of the vessel. 1

2 Claims, 2 Drawing Figures :JOZ U GAS VENT The present inventionrelates to a method and apparatus for unloading a molten product from avessel or tank car and more particularly to a method and apparatus forventing hydrogen sulphide gas from a vessel or tank car containing hotmolten sulphur therein, wherein a layer of sulphur crust has formed onthe upper surface thereof and conventional venting arrangements arenon-functional due to blocking by solidified sulphur.

It is conventional to transport hot molten sulphur in an insulatedrailroad tank car. The car is loaded with the hot molten sulphur whichcontains hydrogen sulphide gas in solution therein. As the sulphur coolsin transit, the hydrogen sulphide gas is released and accumulatesbetween the shell of the car and the crust which forms on the topsurface of the sulphur. There is also a quantity of hydrogen sulphidegas trapped below the crust in the sulphur that remains liquid.Theproblem associated with this accumulation of hydrogen sulphide isthat when the manway cover of the car is opened hydrogen sulphide isreleased therethrough and there have been cases of men being overcome bythe gas and falling from the car. In addition, if the crust ad-DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view, partiallyin section,

illustrating a first preferred embodiment of the present invention; and

FIG. 2 is a side elevational view, partially in section, illustrating asecond preferred embodiment of the present invention.

DESCRIPTION OF APREFERRED EMBODIMENT The present invention provides amethod for unloading molten sulphur from ,a vessel or tank carcomprising the following steps:

1. Passing a hot fluid (i.e. steam) through a conduit passing throughthe crust formed on the top surface of the sulphur so as to melt a holein the crust about the outer periphery of the conduit and to melt anysulphur which may have solidified between the conduit and the vent, thuspermitting trapped hydrogen sulphide gas to pass therethrough.

2. Venting the hydrogen sulphide gas and other gases contained withinthe area above the crust through a conduit having a first end in fluidcommunication with jacent to the manway has become perforated, there isa risk of the pressure of the hydrogen sulphide gas trapped below thecrust causing molten sulphur to be blown up through the perforation.

SUMMARY OF THE INVENTION The primary object of the present invention isto provide a method and apparatus for unloading molten I sulphur from avessel or tank car that eliminates the danger of workmen being overcomeby exiting hydrogen sulphide gas.

Another object is to provide a method and apparatus for venting hydrogensulphide gas from a vessel containing hot molten sulphur therein,wherein a layer of sulphur crust has formed on the top surface thereofand,

molten sulphur therein, which allows air to enter the vessel to permitunloading without having to open the manway cover.

The present invention provides a steam pipe passing through the sulphurcrust adapted to receive steam therethrough. When the steam is passedthrough the pipe a hole is melted through the sulphur crust around theouter periphery of the pipe and solidified sulphur blocking the vent ismelted. The hydrogen sulphide trapped below the crust rises through thehole and is removed along with the gas above the crust through a ventcommunicating with the outside of the vessel. The vent also allows airto enter the vessel to permit the vessel to be unloaded without openingthe manway.

Other objects and features of the invention will become apparent tothose skilled in the art as the disclosure is made in the followingdescription of a preferred embodiment of the invention, as illustratedin the accompanying drawings, in which;

the area above the crust and a second end in fluid communication withthe outside of the vessel.

3. Applying a source of heat to the main coils to heat the sulphur whilethe second end of the vent conduit is in fluid communication with theatmosphere.

. 4. Unloading the sulphur through an unloading valve positioned on thebottom of the vessel. The operation of the above described method willhereinafter become more apparent during the description of two preferredapparatus embodiments which may be used to carry out the above mentionedmethod steps.

, Referring to FIG. 1, a portion of an insulated railroad tank car 10,of the type employed to transport molten sulphur, is illustrated havingan inner tank shell 11, an outer jacket 12, and insulation material 13positioned therebetween. Although not illustrated a conventional mainheat coil is positioned outside of or within the tank to receive steamfrom a source outside the car so as to heat-the sulphur within the car.

The present invention provides a steam pipe 20 passing through the carfrom top to bottom. Since, during transit oil canning or ovalling of theshell occurs, an

'anti compression loop 21 is incorporated in pipe 20. Top portion 22 ofpipe 20 is connected to a source of steam and a control valve (notshown) to permit a selective supply of steam through pipe 20. Bottomportion 23 of pipe 20 is trapped and since the steam passes straightdown through the pipe, no condensate blockage occurs. An elbow vent pipe25, located at the top of tank 11 and jacket 12, is concentric with aportion of pipe 20 and has a first end 26 in fluid communication withthe interior of car 10 and a second end 27 in fluid communication withexterior of car 10. Vent 25 permits fluid communication between theupper portion of car 10 and the atmosphere.-

In operation, as the sulphur within the car cools in transit a sulphurcrust 30 forms on the top surface of the sulphur and a splash crust 3]forms on the tank shell 1 l. invariably sulphur also solidifies betweenvent pipe 25 and pipe 20 effectively blocking the vent to atmosphere andtrapping hydrogen sulphide gas between crusts 30 and 31. Upon reachingthe unloading destinainsulation material tion steam is passed downwardlythrough pipe melting the sulphur between vent pipe and pipe 20. Thehydrogen sulphide gas trapped between crust and crust 31 is thusreleased and exits through vent pipe 25 I to atmosphere. At the sametime a hole 32 is melted in crust 30 and hydrogen sulphide gas trappedbelow crust 30 is released through hole 32 into the area between crusts30 and 31 and then exits through vent pipe 25, as indicated by arrows inFIG. 1. A period of from twenty to thirty minutes is usually sufficientto clear the car of hydrogen sulphide. Steam is then directed throughthe main coils, as well as pipe 20, to raise the temperature of thewhole load of sulphur. When the sulphur is at a suitable temperature forunloading to commence, the bottom unloading valve is opened. As thesulphur flows out of the unloading valve air enters through vent 25 topermit gravity unloading of the car without opening the manway.

Referring to FIG. 2, an alternative embodiment is illustrated inconjunction with a tank car 10. Car 10' includes an inner tank shell 11an outer jacket 12', and 13 positioned therebetween. Although notillustrated a conventional main heat coil is positioned outside of orwithin the tank to receive steam from a source outside the car so as toheat the sulphur within the car.

An inlet steam pipe passing through the car from top to bottomis encasedby an outlet steam pipe 52 having a capped upper end 53. Steam enteringthe bottom of pipe 50 passes upward therethrough into the upper end 53of pipe 52 and then downward through pipe 52 and out lower end 54, asindicated by arrows in FIG. 2. Inlet pipe 50 is fixed to the bottom ofoutlet pipe 52 at 55 in any conventional manner and is centered withinpipe 52 by pipe guides 56 which allow for freedom of differentialexpansion between the two pipes. The upper end 53 of pipe 52 is encasedwith a gas venting pipe 57 which has a first open end 58 just insidetank shell 11 and a second open end 59 outside jacket 12'. Vent pipe 57has capped upper end 60 concentric with upper end 53 of pipe 52. The toppart of pipe 52 is centered within vent pipe 57 by pipe guides 61, whichallow for differential expansion to take place between the top part andbottom part of tank shell 11 Vent pipe 57 is connected to tank shell 1 lin a conventional manner, as by being welded to reinforcement plate 62which is in turn welded to tank shell 11 The operation of thisembodiment in many respects is similar to the operation of theembodiment illustrated in FIG. 1. Upon reaching the unloadingdestination steam is passed upward through pipe 50 and then down throughpipe 52 melting the solidified sulphur between vent pipe 57 and outletsteam pipe 52. The hydrogen sulphide gas trapped between crust 30 andcrust 31 is thus released'and exits through vent pipe 57 to atmosphere.At the same time a hole 32' is melted in crust 30 and the hydrogensulphide gas trapped below crust 30 is released through hole 32 into thearea between crusts 30 and 31 and then exits through vent pipe 57, asindicated by arrows in FIG. 2. A period of from twenty to thirty minutesis usually sufficient to clear the car of hydrogen sulphide. Steam isthen directed through the main coils, as well as pipes 50 and 52, toraise the temperature of the whole load of sulphur. When the sulphur isat a suitable temperature for unloading to commence, the bottomunloading valve is opened. As the sulphur flows out of the unloadingvalve, air enters through vent 57 to permit gravity unloading of the carwithout opening the manway.

Various modifications are contemplated and may obviously be resorted toby those skilled in the art without departing from the spirit and scopeof the invention, as hereinafter defined by the appended claims, as onlya preferred embodiment thereof has been disclosed.

What is claimed:

1. A method for venting hydrogen sulphide gas from a vessel containinghot molten sulphur, wherein a layer of sulphur crust has formed on thetop surface thereof, comprising the steps of:

a. passing a hot fluid through a conduit passing through the sulphurcrust so as to melt a hole in said crust around the outer periphery ofsaid conduit so as to permit trapped hydrogen sulphide gas to passupward therethrough; and,

b. venting'the hydrogen sulphide gas from the area above said crust by aconduit having one end in I fluid communication with said area abovesaid crust and the other end in fluid communication with the outside ofsaid vessel.

2. A method for unloading molten sulphur from a vessel, wherein a. layerof sulphur crust has formed on the top surface of the molten sulphur,comprising the steps of:

a. passing a hot fluid through a conduit passing through the crust so asto melt a hole in the crust about the outer periphery of the conduit andpermit trapped hydrogen sulphide gas to pass upward therethrough;

. venting the hydrogen sulphide gas and other gases contained within thearea above the crust through a conduit having a first end in fluidcommunication with the area above the crust and a second end in fluidcommunication with the outside of the vessel;

c. applying a source of heat to the sulphur while the second end of thevent conduit is in fluid communication with the atmosphere; and

d. unloading the sulphur through an unloading valve positioned on thebottom of the vessel.

2. A method for unloading molTen sulphur from a vessel, wherein a layerof sulphur crust has formed on the top surface of the molten sulphur,comprising the steps of: a. passing a hot fluid through a conduitpassing through the crust so as to melt a hole in the crust about theouter periphery of the conduit and permit trapped hydrogen sulphide gasto pass upward therethrough; b. venting the hydrogen sulphide gas andother gases contained within the area above the crust through a conduithaving a first end in fluid communication with the area above the crustand a second end in fluid communication with the outside of the vessel;c. applying a source of heat to the sulphur while the second end of thevent conduit is in fluid communication with the atmosphere; and d.unloading the sulphur through an unloading valve positioned on thebottom of the vessel.